L7 Pituitary Lesions (Pathology) PDF

1  ILOs Identification of common non neoplastic and neoplastic disorders of anterior pituitary glands Understanding pathology of hyper and hypo fuctioning pituitary gland  The endocrine system widely distributed group of organs that control the metabolic...

1  ILOs Identification of common non neoplastic and neoplastic disorders of anterior pituitary glands Understanding pathology of hyper and hypo fuctioning pituitary gland  The endocrine system widely distributed group of organs that control the metabolic equilibrium between the various organs of the body. Includes: 1. Pituitary gland. 2. Thyroid gland 3. Parathyroid gland. 4. Adrenal cortex. 5. Adrenal medulla. 6. Pineal gland. 7. Pancreas  Endocrine glands The objective of this section of the course is to focus on specific endocrine organs and their respective diseases. Presenting symptoms are either due to : Mass effects Hypofunction of the affected organ. Hyperfunction of the affected organ.  Regulatory Mechanisms Involved in Endocrine Disorders Direct Feedback Cycles Hypothalamic-Pituitary control of endocrine organs  Hypo function of an endocrine organ Destruction of an endocrine gland due to *Inflammation *Infection *Vascular causes: ischemic necrosis, infarction *Neoplastic growth. Because most endocrine glands have significant endocrine reserve, 75-90% of the gland must be destroyed before hypo function appears  Hyper function Tumors, particularly benign ones, can produce hyper function of endocrine organs. One example is an adenoma of the adrenal gland. PITUITARY GLAND  It is Formed of two lobes: A. Anterior pituitary (adenohypophysis) : consists of 3 types of cells: 1 Acidophil cells (35%): secrete growth hormone (GH) and prolactin. 2 Basophil cells (15%): secrete ACTH, TSH and gonadotrophins. 3 Chromophobe cells (50%): non-functioning cells. B. Posterior pituitary (neurohypophysis): act as a store for ADH, which is formed in the hypothalamus. The normal microscopic appearance of the pituitary gland is shown here. The adenohypophysis is at the right and the neurohypophysis is at the left. Non-neoplstic disorders of the anterior pituitary 1-Sheehan's Syndrome (Post-partum Pituitary Necrosis) NEOPLASMS OF THE ANTERIOR PITUITARY GLAND 1Pituitary Adenoma 2Pituitary adenocarcinoma 3-Craniopharyngioma.  Non-neoplstic disorders of the anterior pituitary 1-Sheehan's Syndrome (Post-partum Pituitary Necrosis) Females with massive post partum bleeding will result in hypovolemia and ischemia of pituitary glands……>necrosis and fibrosis of gland….>hypofunction of the gland M/E: Coagulative necrosis, followed by fibrosis  Tumors of the anterior pituitary Pituitary Adenoma Pituitary adenocarcinoma Cranio-pharyngioma.  Pituitary Adenoma N/E: Capsulated, soft, brown mass compressing the surrounding tissue. C/P: (secretory or non secretory) Excess hormone production (acromegaly, gigantism, Cushing syndrome, hyerprolactinemia, hyperthyroidism, rarely gonatropin excess) Large tumors (>1 cm): mass effects (headache, visual disturbances, pressure on surrounding pituitary tissue which may later lead to hypopituitarism) Hemorrhagic necrosis in the gland (surgical emergency) M/E: The cells form solid groups, small acinar or papillary structures. The stroma is fine and vascular. According to the cell type, adenomas may be Chromophobe adenoma``75%" Acidophil adenoma 20%, Basophil adenoma.  Pituitary adenocarcinoma Rare, may complicate Chromophobe adenoma. Destroys the base of sella turcica and extends to nasopharynx.  Craniopharyngioma Site: They are derived from epithelial remnants of Rathke's Pouch. Craniopharyngioma arises in children and young adults and is always benign. N/E: Suprasellar, variable in size, capsulated mass. Cut section shows cystic spaces filled with yellow brown "motor oil" fluid.  M/E: Nests of squamous or basal cells in a loose fibrous stroma. Cystic spaces. Calcification  Effects: 1Compression on the hypothalamus and pituitary gland (hypo-function and related hormone deffeciency). 2 Posterior pituitary Hypo-function. Diabetes insipidus due to deficient secretion of ADH hormone. Presents with polyuria and polydipsia 3 Headache (most common due to mass effect or hydrocephalus)  HYPERPITUITARY SYNDROMES Definition: Hyper function of the anterior pituitary gland Causes: due to either 1- Hyperplasia 2-Adenoma (common) 2- Carcinoma (rare). Effects: l. Hyperprolactinemia (increase prolactin) 2.Gigantism (before closure of the epiphysis) or acromegally (after closure of the epiphysis) (increase growth hormone). 3. Cushing syndrome (increase ACTH). 4- Hyperthyroidism  Hypopituitarism Definition: Hypofunction of the anterior pituitary gland. Causes 1. Congenital anomalies (agenesis-Aplasia-hypoplasia 2. Sheehan's pituitary necrosis 3. Destruction of the pituitary by surgery, radiation or trauma ,pituitary tumors (large adenomas, carcinoma) and brain metastatic tumors. 4. Pressure atrophy by adjacent lesion (e,g craniopharyngioma). C/P: The symptoms of hypopituitarism usually start slowly and get worse over time. But for some patients, symptoms start suddenly. Vary from person to person. Symptoms depend on type of hormone deficiency. Effects 1Pituitary dwarfism (Growth hormone (GH) deficiency) Failure to produce normal amounts of growth hormone in childhood can cause growth problems and short stature 2 Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) deficiency Leads to infertility 3 Thyroid-stimulating hormone (TSH) deficiency Leads to hypothyroidism. 4Adrenocorticotropic hormone (ACTH) deficiency 5- Anti-diuretic hormone (ADH) deficiency diabetes insipidus 6- Prolactin deficiency Decreased milk formation during lactation 7) Simmonds's cachexia. Refers to panhypopituitarism caused by the destruction of the pituitary gland due to infiltrative processes (e.g. lymphocytic), tumours (pituitary adenomas or craniopharyngiomas) or trauma (cranial injury or following surgery). Although cachexia may be present, the disease is characterized by symptoms due to decreased gonadal, thyroidal and adrenal function.  RECOMMENDED REFERENCES 1.Robbins & Cotran Pathologic Basis of Disease, (Robbins Pathology), 2018 ISBN: 978-0-323-35317-5, Edition: 10th 2. Pathmax: http://www.pathmax.com/ 3.Webpath: http://library.med.utah.edu/webpath/webpath.html